Despite the growing body of evidence linking environmental factors to violence and drug exposure, traditional prevention programs have not targeted environmental factors. Instead, intervention programs have typically focused on individuals or families and their high-risk behavior. The proposed investigation seeks to classify both individual- and community-level distributions and determinants of violence and alcohol and other drug (AOD) exposure by identifying environmental factors associated with increased neighborhood violence and AOD exposure among youth. To achieve these goals, independent objective neighborhood ratings will be conducted on a random sample of two unit blocks within each of 277 ecologically defined city neighborhoods to (a) gather information on the physical environment of the neighborhood;(b) clarify the environmental contexts in which youth live and experience violence and AOD exposure;and (c) provide insight on environmental targets for future intervention efforts. To link community-level factors with individual youth violence and AOD exposure, we will also conduct environmental assessments of neighborhoods among the 316 Baltimore youth participating in the Baltimore Prevention Program (BPP). The BPP data are rich in longitudinal information on both violence and AOD exposure as well as social adaptation and psychological well-being from early childhood thru late adolescence. This work will provide a model approach for assessment and identification of environmental factors linked with increased violence and AOD exposure and guide future community-level environmental preventive interventions. This innovative approach to environmental violence and AOD assessment forms the basis for the next stage of research that involves development and implementation of action plans to target specific environmental indicators. As such this investigation initiates a line of inquiry that will advance the evidence base for strategies in program modeling and improve the comprehensiveness and effectiveness of existing programs.